(Adapted from the Applicant's Abstract) The current proposal includes five basic research projects, four clinical research projects,, educational and community support projects, and the Laboratory Core. Clinical diagnosis is handled by the physicians within the Adult Sickle Cell Clinic (Drs. Haynes and Hunter) and Pediatric Sickle Cell Clinic (Drs. Yang, Little, Pace, Gremse) and laboratory diagnosis within the Community Projects Blood Screening Laboratory and the Laboratory Core A at USA. Counseling is provided by the Community Project. Dr. Steven R. Goodman serves as Director of the USA Comprehensive Sickle Cell Center is responsible for all operations with specific oversight of all research projects. Dr. Johnson Haynes serves as Associate Director of Clinical Programs with oversight of the clinical care of 600 children and adults with sickle cell disease who are cared for within USA Sickle Cell clinics and hospital wings. Ms. Rose Peterson is Associate Director for Community Programs.